/*
 * Copyright 2008 Android4ME
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *	 http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.squareup.spoon.axmlparser;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;

/**
 * @author Dmitry Skiba
 *
 * Simple helper class that allows reading of integers.
 *
 * TODO:
 * 	* implement buffering
 *
 */
public final class IntReader {

    public IntReader() {
    }
    public IntReader(InputStream stream,boolean bigEndian) {
        reset(stream,bigEndian);
    }

    public final void reset(InputStream stream,boolean bigEndian) {
        m_stream=stream;
        m_bigEndian=bigEndian;
        m_position=0;
    }

    public final void close() {
        if (m_stream==null) {
            return;
        }
        try {
            m_stream.close();
        }
        catch (IOException e) {
        }
        reset(null,false);
    }

    public final InputStream getStream() {
        return m_stream;
    }

    public final boolean isBigEndian() {
        return m_bigEndian;
    }
    public final void setBigEndian(boolean bigEndian) {
        m_bigEndian=bigEndian;
    }

    public final int readByte() throws IOException {
        return readInt(1);
    }
    public final int readShort() throws IOException {
        return readInt(2);
    }
    public final int readInt() throws IOException {
        return readInt(4);
    }

    public final int readInt(int length) throws IOException {
        if (length<0 || length>4) {
            throw new IllegalArgumentException();
        }
        int result=0;
        if (m_bigEndian) {
            for (int i=(length-1)*8;i>=0;i-=8) {
                int b=m_stream.read();
                if (b==-1) {
                    throw new EOFException();
                }
                m_position+=1;
                result|=(b<<i);
            }
        } else {
            length*=8;
            for (int i=0;i!=length;i+=8) {
                int b=m_stream.read();
                if (b==-1) {
                    throw new EOFException();
                }
                m_position+=1;
                result|=(b<<i);
            }
        }
        return result;
    }

    public final int[] readIntArray(int length) throws IOException {
        int[] array=new int[length];
        readIntArray(array,0,length);
        return array;
    }

    public final void readIntArray(int[] array,int offset,int length) throws IOException {
        for (;length>0;length-=1) {
            array[offset++]=readInt();
        }
    }

    public final byte[] readByteArray(int length) throws IOException {
        byte[] array=new byte[length];
        int read=m_stream.read(array);
        m_position+=read;
        if (read!=length) {
            throw new EOFException();
        }
        return array;
    }

    public final void skip(int bytes) throws IOException {
        if (bytes<=0) {
            return;
        }
        long skipped=m_stream.skip(bytes);
        m_position+=skipped;
        if (skipped!=bytes) {
            throw new EOFException();
        }
    }

    public final void skipInt() throws IOException {
        skip(4);
    }

    public final int available() throws IOException {
        return m_stream.available();
    }

    public final int getPosition() {
        return m_position;
    }

    /////////////////////////////////// data

    private InputStream m_stream;
    private boolean m_bigEndian;
    private int m_position;
}